Rail transport (including without limitation, heavy rail, light rail, monorail, etc.) has been a staple of modern transportation world-wide for nearly 200 years. Aside from high capital costs, rail tends to be a very cost- and energy-efficient mode of transporting both people and cargo.
Typically a rail system will involve infrastructure, including a railway (“track”) that comprises one or more (usually two or three) rails, which anchored on ties or other structural members to provide a consistent gauge (i.e., inter-rail distance) for the track. A set of one or more cars (which, when linked, are colloquially referred to as a “train”) travel over the rails. Generally, each car has an undercarriage that is designed to travel on a specific gauge of track, and there are several standardized gauges of track.
The gauge (and other factors, such as relative elevation of each rail, shape of each rail, etc.) can be considered the “track geometry” or “rail configuration” of the railway. In most rail systems, the rail configuration must fall within specified tolerances, which are generally quite precise; if the track geometry falls outside those tolerances, there is a significant risk of railcar derailment, which often produces catastrophic results.
Accordingly, several different solutions have been proposed to ensure a satisfactory rail configuration. One such solution is manual inspection, but the relatively long distances involved in most railways render this solution unacceptably labor intensive and therefore impracticable. Another solution involves the use of mechanical sensors, which are generally mounted on special cars that travel the railway to monitor track geometry. More recently, optical solutions, which employ lasers to probe track geometry, have been proposed. The use of mechanical and/or optical sensors, however, can prove to be prohibitively expensive, and such solutions often require specialized hardware, traveling on specialized rail cars, reducing their utility further.
Hence, there exists a need for a relatively inexpensive, automated solution to the problem of track geometry monitoring.